At this point in the story the black flame is the most popular and effective offensive and NOW defensive attack at his disposal. The stronger ninjas are dispelling his Tsukuyomi techniques by pumping themselves with uber amounts of chakra or however the hell Raikage countered Sasuke's latest genjustu attempt on him.(Maybe you can give me an explanation on that) Another reason why I think Sasuke favors Amaterasu is because he learned he can put out the flames therefore making the technique more flexible adding his own creativity to how it is unleashed.Originally Posted by The Chancellor